Golf ball finishing method

ABSTRACT

A method of removing parting line flash from a molded golf ball by use of low temperature cryogenic deflashing apparatus is disclosed. The cryogenic deflashing apparatus incorporates a rotating basket wherein the golf balls are placed and therein agitate them such that each ball will be evenly exposed to a recirculating blasting media. The low temperature environment causes the very thin gauge (0.003″) parting line flash to become embrittled relative to the ball and is deflashed by the blasting media, which comprises plastic pellitized shot.

FIELD OF THE INVENTION

[0001] The invention relates to an improved method for finishing thesurface of golf balls. More specifically, the improvement is directed tothe removal of parting line flash from molded golf balls by a cryogenicdeflashing apparatus.

BACKGROUND OF THE INVENTION

[0002] Conventional golf balls can be divided into two general types orgroups: solid balls and wound balls. The difference in playcharacteristics resulting from these different types of construction canbe quite significant.

[0003] Balls having a solid construction are generally most popular withthe average recreational golfer because they provide a very durable ballwhile also providing maximum distance. Solid balls are generally madewith a single solid core, usually made of cross-linked rubber, which isencased by a cover material. Typically the solid core is made ofpolybutadiene which is chemically cross-linked with zinc diacrylicand/or similar cross-linking agents and is covered by a tough, cut-proofblended cover. The cover is generally a material such as SURLYN®, whichis a trademark for an ionomer resin produced by DuPont. Wound ballstypically have either a solid rubber or liquid center core around whichmany yards of stretched elastic are wound. Wound balls are generallysofter and provide more spin, which enables a skilled golfer to havecontrol over the ball's flight and final position.

[0004] Regardless of the form of the ball, players generally seek a golfball that delivers the best combination as to maximum distance, spin anddurability. Golf ball manufacturers are continually searching for newways in which to provide golf balls that deliver the maximum performancefor golfers at all skill levels.

[0005] The outer cover of either type golf ball are formed with variousmaterials that may be urethane elastomers, Balata, ionomers or any otherappropriate materials. The cover surfaces are formed with dimples ofvarious numbers, sizes and patterns, which improve flight distance,control and stability. The outer surface of the ball covers usually havethe manufacturers indicia disposed thereon as well as an application ofa paint or clear coat for the purposes not only of good appearance butalso of improving fight distance and protecting of the indicia imprintedthereon.

[0006] The process of molding a cover over a golf ball subassemblyusually produces a golf ball having a parting flash line, i.e. the areaadjacent the interfacing mold surfaces. Such residual flash is not onlyaesthetically objectionable, but additionally functionallyobjectionable, and therefore must be removed, i.e. deflashed, from thearticle prior to use of the same. It has been necessary to perform abuffing or finishing step to remove this flash. The prior art method ofremoving the flash is to employ mechanical cutting blades and sandpaper.This method requires a high level of intervention due to belt and bladewear and also requires precise orientation of the subassembly on thebuffing equipment. A method of finishing golf balls in a bulk processwithout the need for mold orientation of balls is highly desired.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to an improved method ofremoving parting line flash from a golf ball component following themolding of a layer on a ball subassembly. The process is preferably usedfor deflashing golf balls after the cover layer has been molded onto theball subassembly. The process is most preferably used for non-planarparting lines. The invention allows for golf ball coponents to be bulkloaded into a cryogenic chamber where the temperature of the ball isreduced by liquid nitrogen. Operating temperatures are typically below−100° F. Because of the thin gauge of the parting line flash relative tothe layer thickness, (the gauge of the flash generally only about 0.003inches) the flash becomes embrittled in comparison to the layer. Thechamber contains a rotating tumbler to agitate and expose the golf ballcomponents during the flash removal cycle. As the chilled productrotates a plastic media is delivered at high velocity which furtherenhances the flash removal process.

[0008] The present invention provides for the removal of flash lines ina batch method therein eliminating the need for orienting each golf ballprior to deflashing, and also eliminating the need for orientation tabs.

[0009] The present invention reduces the maintenance and downtime due tochanging and replacing sanding belts and cutting blades.

[0010] Batch buffing allows for bulk loading and unloading therebysimplifying the material handling process.

[0011] The present invention allows for easier finishing of varyingsymmetry of parting lines and dimple patterns.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 describes a process flow chart for the present invention'smethod for golf ball finishing.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013] The present invention applies to all thermoplastic or thermosetlayers on golf balls that require finishing or removal of flashing thataccrues from the molding of the layer on a golf ball subassembly.

[0014] In the manufacture of golf balls, flash lines are routinelyremoved by mechanical buffing procedures in which mechanical cuttingblades and sand paper are utilized as a buffing medium. The orientationof the ball is of primary importance for the buffing step. Orientationtabs are typically molded into the ball to accommodate this requirement.The replacement of belts and blades adds to the significant interventionrequired for these procedures. With the advent of future golf ballshaving irregular flash lines (non-planar), there is a strong need for amethod for removing the flash without having to orient the balls for abuffing process. The present invention utilizes a cryogenic process thatdoes not require orientation of the golf balls in order for the flash tobe removed, and also eliminates the need for sandpaper and cuttingblades.

[0015]FIG. 1 displays a flow chart wherein golf balls are moved fromcompression mold racks by automatic transport to a bulk die-out. Fromthere they are transported to a cryogenic apparatus and placed into astainless steel parts basket of the apparatus. The parts basket rotatesin a blast chamber evenly exposing all golf balls to the blast media.The chamber is insulated with rigid polyurethane foam to ensure stabletemperatures. Liquid nitrogen lowers the interior temperature, freezingthe flashing to make it brittle. Use of high purity, moisture-freenitrogen eliminates the need for a dryer and prevents part contaminationdue to moisture. A high speed impeller introduces a blasting mediatypically comprising pellitized shot. Operating temperatures aretypically below −100° F., preferably in a range between about −100° F.to about −220° F., and more preferably about −190° F. The process timeis about ten minutes.

[0016] The parting line flash is of a rather thin gauge (0.003 inches)relative to the thickness of the molded cover, and therefore only theparting line flash becomes embrittled in the low blasting media stream.By controlling the exposure duration of the molded golf balls within thecryogenic environment, as well as the velocity and dispersion of thedeflashing media against them, it has been found that satisfactory golfball deflashing may be accomplished, typically at a substantialreduction over sanding deflashing operations. After the flashing hasbeen removed the balls are bulk unloaded for further processing.Acceptable cryogenic equipment includes machines such as thosemanufactured by Cryogenic Deflashing Systems, Inc. of Santa Ana, Calif.,and based upon the teachings of U.S. Pat. No. 4,979,338, which isincorporated by reference herein in its entirety.

I claim:
 1. A method for removing parting line flash from golf balls,the method comprising: loading a plurality of golf ball components withflash into a rotating tumbler within a cryogenic chamber; agitating thetumbler to expose the surfaces of the golf ball components; loweringtemperature in the chamber to less than about −100° F.; introducingplastic media into the chamber to remove the flash; and removing thegolf ball components from the chamber.
 2. The method of claim 1, whereinthe step of lowering the temperature of the chamber is by theintroduction of high-purity, moisture-free liquid nitrogen into thechamber.
 3. The method of claim 2, wherein the lowering of thetemperature in the chamber is to a temperature of between about −100° F.and about −220° F.
 4. The method of claim 1, wherein the plastic mediaare particles with an average diameter less than about xxx inches. 5.The method of claim 1, wherein the golf ball components are exposed forless than xxxx minutes.
 6. A golf ball produced by the method of claim1.